9-carboxylic naphthoxazoles and plastics brightened therewith

ABSTRACT

Naphthoxazoles characterized by the presence of a carboxylic function at the 9-position are provided. They are improved mass brighteners for molded plastics, particularly polyesters, since they absorb strongly in the UV region of 370-400 nanometers and do not sublime or mark off at high molding temperatures. They correspond to the formula     D R A W I N G IN WHICH R1 is the hydroxyl radical, or, a monovalent dehydro radical of an alcohol, a phenol, a primary amine or a secondary amine, said monovalent radical containing about 1-8 carbon atoms, and Y is a 2-naphthoxazolyl, or a 2-naphthoxazolylphenyl having a carboxylic acid function at the 9-position, a stilbyl, a 2benztriazolylphenyl or a 2-naphthtriazolylphenyl radical, or a styryl, 4-cyanostyryl or 4-carboxystyryl radical.

mated States patent m] ue I [54] 9-CARBOXYLIC NAPHTHOXAZOLES ANDPLASTICS BRIGHTENED THEREWITH [75] Inventor: Bennett George Buell, BoundBrook,

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: June 11, 1970 [21] Appl. No.: 45,595

[52] US. Cl ..260/307 D, 106/204, 117/126 GE, 117/127, 117/130 R,252/3012 W, 260/75 R, 260/78 R, 260/92.8 R, 260/93.7, 260/94.9

R, 260/240 D, 260/562 P [51] Int. Cl. ..C07d 85/48 [58] Field of Search..260/240 D, 240 CA, 307 D Primary Examiner-John D. RandolphAttorney-John L. Sullivan 1 Feb. 20, 1973 [5'71 ABSTRACT Naphthoxazolescharacterized by the presence of a carboxylic function at the 9-positionare provided. They are improved mass brighteners for molded plastics,particularly polyesters, since they absorb strongly in the UV region of370-400 nanometers and do not sublime or mark off at high moldingtempera tures. They correspond to the formula mil in which R is thehydroxyl radical, or, a monovalent dehydro radical of an alcohol, aphenol, a primary amine or a secondary amine, said monovalent radicalcontaining about l-8 carbon atoms, and Y is a 2- naphthoxazolyl, or aZ-naphthoxazolylphenyl having a carboxylic acid function at the9-position, a stilbyl, a

2-benztriazolylphenyl or a Z-naphthtriazolylphenyl.

radical, or a styryl, 4-cyanostyryl or 4-carboxyst'yryl radical.

7 Claims, No Drawings 4 9-CARBOXYLIC NAPHTHOXAZOLES AND PLASTICSBRIGHTENED THEREWITH This invention relates to naphthoxazole compoundsand more particularly to certain naphth[ l,2-d]oxazole 5 derivativescharacterized by the presence of a carboxylic function at the 9-positionthereof. The invention includes the new 9-carb0xylic naphthoxazoles,which are improved brighteners or optical bleaches for moldedthermoplastic polymers, their methods of 10 preparation, and improvedplastics wherein they are distributed in brightening amounts.

The new naphthoxazoles are compounds having the ormu a in which R isstyryl, benztriazol-Z-yl or naphthtriazol- 2-yl.

2. Radicals of the formula --CH=C III-@R in which R is hydrogen, cyano,0r COR wherein R is as defined above.

3,4. Radicals 0f the formulas wherein R is as defined above.

In addition to their characterizing light absorption, these compoundsalso form a group that can be prepared from the same common startingmaterial. This is an important commercial advantage. The startingmaterial is 4-amin0-3-hydroxy-2-naphth0ic acid, which is readilyprepared from the 3-hydroxy-2- naphthoic acid of commerce. A preferredpreparation is by coupling a phenyldiazonium salt to the 3-hydroxy-Z-naphthoic acid followed by reduction with sodium hydrosulfite.

Synthesis of a brightener containing a free carboxylic acid at the9-position of the naphth[ l ,2-d]oxazole radical or radicals is thencompleted by an appropriate method as described below and illustrated inthe accompanying examples. Conversion of this group to the correspondingester or amide may be accomplished by any standard acylation oramidation procedure, but the brightener is preferably first convertedinto its acid chloride which is reacted with at least astoichiometrically equivalent amount of an alcohol or a primary orsecondary amine. Best results have been obtained with alcohols andamines containing from one to eight carbon atoms such as the following.

Alcohols suitable for the practice of this invention are: alkanols ofone to eight carbon atoms such as methanol, ethanol, Z-methoxyethanol,2ethoxyethanol, propanol, isopropanol, l-butanol, isobutanol,l-pentanol, 2-methylpentanol, and S-ethylhexanol; alkenols such as allylalcohol; cyclic alkanols and cyclic alkenols 0f 1 to 8 carbon atoms suchas cyclopentanol, cyclohexanol and 2-cycl0hexen-l-0l; phenols such asphenol itself, 0-, mor p-anisole, 2-, 3- or 4-hydroxytoluene or othersubstituted phenols in which hydroxy is the only substituent having anaction hydrogen; dihydric and trihydric alcohols such as ethyleneglycol, propylene glycol and glycerine.

Primary amines suitable for the practice of this invention are:aliphatic amines such as normal, branched and substituted amines of oneto eight carbon atoms and arylamines of the benzene series such as:

melhylamine aniline ethylamine 0-, mand p-anisidine isopropylamine 0-,mand n-propylamine p-chloroaniline n-butylamine 0-, mand p-cyanoanilineisobutylamine 0-, mand sec-butylamine p-toluidine n-octylamine 0-, mandp-trifluoroaniline n-dodecylamine 0-, mand n-octadecylaminep-aminobenzoic acid ethanolamine 0-, mand p-aminobenzoic monoestersisopropanolamine 0-, mand cyunoethylamine p-aminobenzoic monoamides2-carbamoylethylamine 3-[2cthoxy( 2- ethoxy) lpropylamine Secondaryamines suitable for the practice of this invention are: aliphatic,cycloaliphatic and heteroaromatic amines of 1-8 carbon atoms such as:

dimethylamine diethylamine di(isopropyl)amine bis( 2-methoxyethyl )aminebis( 2-cyanoethyl )amine bis( 2-hydroxyethyl )amine bis(2-carbamoylethyl)amine morpholine pyrrolidine 5 piperidine N-ethyl-N-(Z-carbamoylethyl )amine N-( 2cyanoethyl )-N( 2-carbamoylethyl )amineN-(2-cyanoethyll-N-(2-hydroxyethylamine) N-Methyl-2-hydroxyethylamine l0N-Methyl-N-(Z-carbamOylethyDamineN-(2-hydroxyethyl)-N-(2-carbamoylethyl)amine A preferred subclass ofcompounds is represented by Formula 1 m T o 31-4") R.1 o o representedbyformula ll; 35 II a) wherein R is as defined above and R is styryl,benztriazolyl or naphthtriazolyl. These are illustrated in Table ll.These compounds are prepared by reaction of4-amino-3-hydroxy-2-naphthoic acid with an acid chloride followed bycyclization of the resulting amide with acid reagents such aspolyphosphoric acid or a dodecylbenzene sulfonate. This gives the2-stilbyl-, 2- benztriazolylphenyl-, or,Z-naphthtriazolylphenylnaphthll,2-d]oxazole-9-carboxylic acid which arecompounds of this invention. These can be converted to ester or amidederivatives of the 9-carboxylic acid by standard acylation or amidationprocedure, as-illustrated in the examples.

A third preferred subclass of compounds represented by Formula Ill:

ill 0 R l wherein R is as defined above and R is hydrogen, cyano or COR.These compounds, illustrated in Table lll, may be prepared in either oftwo ways:

1. The reaction of 4-amino-3-hydroxy-2-naphthoic acid with acinnamaldehyde to form a cinnamal Schiff base followed by oxidativecyclization. R is defined as above.

2. Acylation of 4-amino-3hydroxy-2-naphthoic acid with acetic anhydrideand the product cyclized with acid-catalyzed reactions to give a newintermediate, 2- methylnaphth[ l ,2-d]oxazole-9-carboxylic acid. This iscondensed with a compound wherein R is defined as above, in the presenceof an acid catalyst to give the 2-(p-R -styryl)-naphth[1,2-d]oxazole-9-carboxylic acid which is a compound of this invention. Thefree acid can be converted to an ester or amide by standard acylation oramidation procedures as illustrated by example.

A fourth preferred subclass of compounds is represented by Formula iv: v

wherein R is as defined above. These are illustrated in the Examples andTable IV.

These are synthesized by condensation of 4-amino-3- hydroxy-Z-naphthoicacid with glyoxal to give the bisdihydronaphthoxazole. This is oxidizedwith sodium hypochlorite to the sodium salt of the bis-naphthoxazole,which is converted to the free acid or to the acid chloride, followed byreaction with an alcohol or a primary or secondary amine.

In converting the free carboxylic acid compounds of preferred subclassesI, ll, lll and IV, the carboxylic acid may be reacted with an excess ofthionyl chloride serving as both solvent and chlorinating agent. Theisolated acid chloride in a solvent such as xylene, benzene or pyridine,is reacted with alcohol or with a primary or secondary amine to form acarboxylic ester or amide, respectively.

The four classes of compounds I, II, III and iv are useful asbrighteners of thermoplastics such as polyester, poly(vinyl chloride),polypropylene,

Most of the pyridine is distilled off. It is cooled, the productfiltered, washed with pyridine, water, and dried at 60C. There isobtained 4.45 g. product, m.p. 242246C.

The product is recrystallized from a monochlorobenzene-butanol mixture,chromatographed on alumina from chloroform and recrystallized again fromMCB-butanol. It melts at 248-249C. and shows a 380 113.8 in its UVspectrum.

When methanol is substituted for n butanol in this preparation thecorresponding dimethyl ester is obtained. lts melting point andwhiteness are listed in Table 1.

EXAMPLE 3 Preparation of 1,4-bis [9-di(2-methoxyethyl)carbamoyl]naphth-[ 1,2-d]oxazol-2-yl benzene A mixture of10.0 g. of the product of Example 1 and 200 ml. thionyl chloride isrefluxed for 24 hours. The excess thionyl chloride is then completelyremoved by vacuum distillation to give a residue that shows the correctIR spectrum for the acid chloride of Example 1. The residue is taken upin 250 ml. pyridine and 15 ml. bis-(2-methoxyethyl)amine is added. Themixture is refluxed one half hour, cooled, poured into 1 liter of iceand water and then filtered. Finally after washing with water, theproduct is dried in vacuo at 60C. Final weight 9.60 g., m.p. l88l92C.The IR spectrum confirms the product. Chromatography on alumina fromCHCl and recrystallization from methoxyethanol gives 6.25 g. of pureproduct, 208.5-209.5C.

EXAMPLES 4-6 Products wherein other amines are substituted for thebis-(2-methoxyethyl)amine of Example 3 are prepared by the procedure ofthat example. Representative amines, and the melting points andHunterlab meter whiteness values of the products obtained, are listed inTable l.

EXAMPLES 7-15 Type Formula II (II) R C TABLE 2 Example Melting White-No. R R Point C. ness 7 0H Styryl 302-15 98.4 8 -OC.H Styryl 142.7 85.69 Nl-lC,l-l, Styryl 238-9 84.6 10 NHC H, Styryl 206.8 91.7 1 I --OHNaphth[1,2-d] 343-5 64.2

triazol-Z-yl l2 ---OC,H Naphthl l,2-d] 240-2 100.7

triazol-Z-yl l3 N(CH,CH,OCH.-,), Naphth[ l ,2-dl 225- 6 92.6

triazol-2-yl l4 ---OC H Benztrlazol-2-yl 216 -7 89.7 -N(CH,CH.OCH,BenztrlamI-Z-yl 196-8 86.8

These compounds are prepared by reaction of 4-amino-3-hydroxy-2-naphthoic acid with an acid chloride followed bycyclization of the resulting amide with acid reagents such aspolyphosphoric acid or a dodecylbenzene sulfonate. This gives the2-stilbyl-2- benzotriazolylphenyl-, or,Z-naphthotriazolyl-phenylnaphth-ll,2-d]oxazole-9-carboxylic acid whichare compounds of this invention. These can be converted to ester oramide derivatives of the 9-carboxylic acid by standard acylation oramidation procedure, as illustrated in the examples.

EXAMPLE 7 EXAMPLE 8 A mixture of 1 gram of the product of Example 7 and25 ml. of thionyl chloride is heated with stirring. The excess thionylchloride is removed and the residue is taken up in ml. of pyridinecontaining 5 ml. of nbutanol. The mixture is heated under refluxuntilesterification is complete after which the pyridine is distilledofi. The residue is cooled, washed with pyridine and dried. Ananalytical sample is obtained by the purification procedure described inExample 2.

EXAMPLES 9-10 Preparation of 9-N-phenylcarbamyl-2-stilbylnaphth[l,2-d]oxazole A mixture of 4.36 g. 4-stilbenecarbonyl chloride and 5.00g. heated in pyridine solution on the steam bath for a half hour. Theproduct is isolated by cooling, drowning in ice water and filtering.There is obtained 9.8 g. of the crude amide. The crude product, 8.72 g.is mixed with 1.1 l g. boric acid and heated at 240C. for 20 minutes.After cooling, the fusion product is ground in a mortar andrecrystallized several times from methyl cellosolve. The product meltsat 238239C. The .UV spectrum shows a 1 15.5. An analytical sampleshows a310 m 121.2. Maximum emission peaks occur at wavelengths of 434 nm and457 nm. This product brightens polyethylene, polyvinyl chloride andpolyester plastics.

Substitution of l -amino-3-n-butylcarbamyl-2- naphthol in thispreparation gives 9-n-butylcarbamyl-2- stilbylnaphth-[ l,2-d]oxazole,the melting point and whiteness of which are listed in Table 2.

EXAMPLE 1 1 Preparation of 2-(Naphtho[l,2-d]triazol-2?yl)-9-carboxynaphth-[ l ,2-d1oxazole 1-amino-3-N-phenylcarbamyl-2-naphthol ispolyethylene, poly(methyl methacrylate) and polyamides such as nylons. Apreferred use is in polyester dope or melt composition used forspinning, extruding or moulding into fibers, films, tubing, and otherforms of articles. About 0.005 to 1.0 weight percent of the brightenercompound is incorporated by mixing in molten polyester at about280290C., and thereafter shaping and cooling. A strong whitening effectis observed in the shaped polyester as well as a brilliant bluefluorescence. The brightener compounds of this invention are distinctfor their lack of sublimation from such substrates. I

The advantage of incorporating the compounds of this invention in theplastic is the permanence of the brightening compared to after treatmentof the surface with a brightener.

Most of the brightener compounds of this invention absorb strongly inthe UV region of 370-400 nanometers as contrasted with 340-369nanometers for other brighteners. This gives a much higher whiteningstrength in polyester both as measured by instruments and as seen by theeye.

The lower absorbing members may find use as donor components forbrightener systems which depend ,on transfer of energy from donorbrightener to acceptor brightener in molten polyester masses.

The compounds having free carboxylic acid groups have affinity forcotton and other cellulosic textile fibers.

The invention will be further described and illustrated by the followingspecific examples, wherein the preparation and testing of representativecompounds is described and wherein wavelengths are expressed asnm"(nanometers). in the tables of these examples the term whitenessindicates the test results obtained by the following procedure.

A chip of polyester (polyethylene terephthalate) containing thebrightener compound to be evaluated, is prepared as follows. Thepolyester is dry-blended with 0.04 percent by weight of the brightenerin a ball mill for 24 hours. The coated flakes are dried in an oven for24 hours at 212F. The dried flakes are placed. in a cavity mold. Themold is placed in a hydraulic press heated at 575F. and subjected to apressure of 30 tons on a 4.5 inch diameter for 2 minutes. This forms achip of 45 to 46 mils thickness. Measurements of whiteness of thepolyester chip are made on a l-lunterlab Color and Color DifferenceMeter, Model D-25M quipped with a 45-0 optical unit with circumferentialillumination and direct reading whiteness module. This instrument makesprecise measurements of the color of flat sur faces as they appear inday-light. Values of color are read directly from digital dials. Thedegree of whiteness is based on the relationship of the lightnessmeasurement to the yellowness-blueness measurement and is expressed as:

where W is whiteness L is lightness b is yellowness-blueness A controlchip lacking any brightener compound has a whiteness of about 58.3.

EXAMPLES l-6 4- lype Formula I 1? Ii R C C-R 1 0 0 1 O} N N lo] TABLE 1Example No. R Melting White- Point C. ness 1 -OH Over 300 79.4 2-O(CH,),Ch, 248-9 104 2a -OCH, 346-350 88.9 3 --N(cH,c1-l,oct-|, 208-993.0 4 N(CH,CH,CN), 337-9 96.5 s -Nn(cn, ,o cn, ,oc,n, 293-5 94.4 6 over3 l0 90.4

These compounds are prepared by the reaction of two moles of4-amino-3-hydroxy2-naphthoic acid with one mole of terephthalaldehyde,followed by oxidation with nitrous acid in situ to give the1,4-phenylene-bis- (naphth[1,2-d]oxazole-9-carboxylic acid). The freeacid, one of the brightener compounds of this invention, is converted toits ester or amide by standard acylation or amidation procedures, asillustrated in the examples.

EXAMPLE 1 Preparation ofl,4-bis(9-carboxynaphth[l,2-d]oxazole-2-yl)benzene .A mixture of 8.12 g.0.04 mole)of the known compound, 4-amino-3-hydroxy-2-naphthoic acid, and200 ml. acetic acid is heated to 50C. with stirring. Then, 2.68 g. (0.02mole) terephthaldialdehyde is added and the mixture heated to boiling.It is cooled to 15C. and 2.90 g. (0.04 mole) sodium nitrite addedgradually. During 2 hours of stirring the mixture gradually changes fromtan to yellow. The mixture is heated to C. becoming still lighter incolor. It is filtered warm and the precipitate washed with acetic acidand with water. Dried at 60C., it gives 9.0 g. of product, mp. 300C. Theinfrared spectrum confirms the product.

A purified sample prepared by charcoal treatment of a solution of thedisodium salt and precipitation as the free acid by addition ofhydrochloric acid, has an absorptivity at 380 nm. of 102.2. in additionto its application in polyester melt or mass brightening, it brightenscotton.

EXAMPLE2 Preparation of dibutyl l,4-phenylene-bis(naphth[l,2-d]oxazol-2-yl-9-carboxylate) A mixture of 5.00 g. of the product ofExample 1 and 100 ml. of thionyl chloride is heated with stirring. Theexcess thionyl chloride is removed and the residue taken up in ml.pyridine and 5 ml. n-butanol. The mixture is heated to reflux. 1

The acid chloride of the known 2-(4-carboxyphenyl) naphthotriazole isprepared by a standard procedure. A solution of 6.31 g. of this chloridein 200 ml. xylene is combined with a solution of 4.14 g.4-amino-3-hydroxy-Z-naphthoic acid in 400 ml. xylene and 50 ml.dimethylformamide and heated at reflux for 20 hours, concentrated andprecipitated with petroleum ether. The product is filtered and driedgiving 8.68 g. of crude product. Recrystallization from 1,200 ml.dichlorobenzene gives 7.21 g., m.p. 357-360C. of amide. To cyclize thisamide, 7.00 g. is taken up in 200 g. polyphosphoric acid and the mixtureis heated at 183C. for 4 hours. The product is isolated by cooling anddrowning in water. After repeated recrystallization frommonochlorobenzene, it melts at 352354C. lts UV spectrum: a 108.6. ltswhiteness value in polyester melt is given in Table I1.

EXAMPLES 12-13 Preparation of 2-(Naphtho[ l,2-d]triazol-2-yl)-9-carbutoxy naphth[ l ,2-dloxazole The acid chlorideof Example 1 l is prepared by standard procedure. Then 1.50 g. of thechloride is combined with 25 ml. of pyridine and 1.40 ml. of n-butanol.The solution is refluxed 12 hours, cooled and filtered. The crude yieldis 1.34 g. Repeated recrystallization from n-butanol gives 0.61 g., m.p.240-242C.

UV spectrum: a m 106.1; a 96.7

Substitution of bis-(2-methoxyethyl)amine for the nbutanol gives2-(naphtho[ l ,2-d]triazol-2-yl)-9-[di-(2-methoxyethyl)]carbamoy1naphth[ 1 ,2-d]oxazo1e, the properties of whichare described in Table 2.

EXAMPLES 14-15 Preparation of n-Butyl 2-(2H-benzotriazol-2-yl)- naphth[l,2-d]-oxazole-9-carboxylate A. Preparation of4-(ZH-Benzotriazol-Z-yl)-benzoic acid To 72.4 g. m-phenylenediaminedihydrochloride in a liter of water is added a solution ofp-carboxyphenyldiazonium chloride prepared by diazotizing 54.8 g.paminobenzoic acid by standard methods in dilute hydrochloric acid togive a liter of clear solution. With stirring, a saturated solution ofsodium acetate is added slowly until the mixture is neutral to Congo Redindicator paper. When coupling is complete, the product is filtered andtaken up in 1 liter of l 1 aqueous pyridine. Triazolization is effectedwith 60 g. cupric acetate followed by 25 g. cupric sulfate. There isobtained 89.4 g. 4-(5-amino-ZH-benzotriazol-Z-yl)-benzoic acid which isdeaminated as follows: 12.7 g. of the latter is dissolved in aqueousalkali, 3.5 g. sodium nitrite added, and the mixture diazotized bypouring into dilute hydrochloric acid solution at l 5C. To the mixture,50 ml. hypophosphorous acid is added. The whole is stirred for 72 hoursas nitrogen slowly evolves. The product (A) is filtered, washed withwater and dried to give 11.12 g. m.p. 3l8320C.

B. Preparation of 2-(2l-l-benzotriazo1-2-yl)- naphth[1,2-d]-oxazole-9-carboxylic acid Product (A) is converted to its acidchloride by use of thionyl chloride in standard procedure. The acidchloride, 0.01 mole is added to 2.10 g. 4-amino-3- hydroxy-2-naphthoicacid dissolved in 50 ml. pyridine. After 1 hour of reflux, the amideproduct is isolated by cooling and precipitating with water. It iscyclized to the oxazole by heating in orthodichlorobenzene with acatalytic amount of ammonium dodecylbenzenesulfonate.

C. Esterification to the butyl carboxylate.

Product (B), 2.55 g. is heated with 5 ml. n-butanol in 250 ml. xylenecontaining a catalytic amount of dodecylbenzenesulfonic acid. After 24hours of reflux with water separator attached, the product is isolated.Purification is effected by recrystallizing fromorthodichlorobenzene-butanol mixtures, chromatography on alumina fromchloroform and recrystallization from n-butanol. The product melts at216-2l7C. and is confirmed by infra red spectrum and elemental analysis.Substitution of bis-(2-methoxyethyl)amine for the n-butanol gives thecorresponding amide.

EXAMPLES 16-24 The compounds of Formula 111 may be prepared by either oftwo ways:

1. The reaction of 4-amino-3-hydroxy-2-naphthoic acid with acinnamaldehyde to form a cinnamal Schiff base followed by oxidativecyclization. R is defined as in Table 3.

2. Acylation of 4-amino-3-hydroxy-2-naphthoic acid with acetic anhydrideand the product cyclized with acid reagents to give a new intermediate2-methylnaphth[l,2-d]oxazole-9-carboxylic acid. This is condensed with acompound wherein R is defined as above, in the presence of an acidcatalyst to give the 2-(p-R -styryl)-naphth{1,2- d]oxazole-9-carboxylicacid which is a compound of this invention. The free acid can beconverted to an ester or amide by standard acylation or amidationprocedures as illustrated by the examples.

EXAMPLES 16-1 9 Preparation of 9-carboxy-2-styrylnaphth[l,2-d]oxazole Amixture of 10.1 g. 4-amino-3-hydroxy-2-naphthoic acid,-6.4 g.cinnamaldehyde, 200 ml. acetic acid and 5 ml. of 5N hydrochloric acid isheated to 90C. and allowed to cool to room temperature with stirring.Sodium nitrite, 3.5 g., is added and after 5 minutes of stirring, 1.0 g.more added. The mixture is heated to 50C. and allowed to cool. Theproduct is filtered, washed with acetic acid, then water, and dried at60C. there is obtained 8.91 g. of material, m.p. 262266C. having thecorrect IR spectrum.

An analytical sample melts 270-272C. The whiteness value is in Table 3.

In addition to melt brightening of polyester, this brightener is alsouseful as a donor component for brightener systems which depend ontransfer of energy from donor brightener to acceptor brightener inmolten polyester masses.

Portions of this product are converted into the corresponding esters oramides by the procedures described in Examples 2 and 3 respectively. Themelting points and whiteness values of the products are shown in Table3.

EXAMPLE 20 Preparation of 2-(p-carboxystyryl)-9-carboxynaphth[ l,2-d]oxazole a. Preparation of the intermediate 9-carboxy-2-methylnaphth-[ l,2-]oxazole A mixture of 6.09 g.4-amino-3-hydroxy-2-naphthoic acid, 3.10 acetic anhydride, 150 ml.xylene and 2 drops pyridine is heated at gentle reflux for a half hour.A solution of ammonium dodecylbenzene sulfonate prepared from 5 ml.dodecylbenzene sulfonic acid in 100 ml. xylene is added. The mixture isheated at reflux with a water separator attached, until no more watercomes over. The mixture is cooled, filtered and the product washed withbenzene. it is dried at 60C. to give 6.48 g. product. Recrystallizationfrom 300 ml. orthodichlorobenzene gives 5.46 g. product m.p. 295-295.5C.

b. Preparation of Z-(p-carboxystyryl)-9-carboxynaphth[ l ,2-d]-oxazole Asolution of ammonium dodecyibenzene sulfonate is prepared by boiling amixture of 2 ml. dodecylbenzene sulfonic acid, 2 ml. of cone. ammoniumhydroxide and 300 ml. 1,2,4-trimethylbenzene until all the water hasbeen removed. To this solution is added 4.54 g. of the product of (a)and 3.20 g. terephthalaldyhydic acid and the mixture is refluxed forabout 3 hours until all of the water has been removed. The mixture iscooled, the precipitate washed with benzene and dried at C. There isobtained 6.91 g. of olive-green solid having a confirmatory IR spectrum.Two recrystallizations from diglyme give a yellow solid, m.p. 350-35 1C.

, EXAMPLE 21 Preparations of Z-(p-carbutoxystyryl)-9-carbutoxynaphth[ l,2-d1-oxazole A mixture of 1.00 g. of the product of Example 20(b) and40 ml. thionylchloride is refluxed for two hours. The excess thionylchloride is removed in the usual manner and the residue is taken up in40 ml. of pyridine and 2.0 ml. of freshly distilled n-butanol. After anhour of reflux the product is isolated by cooling and drowning in water.The product is filtered, dried and chromatographed on alumina fromchloroform. It is recrystallized from n-hexane to give a I light yellowproduct, m.p. 9 l-92C.

The UV spectrum shows a 81.4.

The whiteness value is in Table III.

This product not only brightens polyester but is also excellent forbrightening polyethylene and polyvinylchloride. It also brightens nylon.

EXAMPLES 22-24 Other products containing the substituents shown inExamples 22 and 23 of Table 3 are prepared by the same procedure as inExample 21 except for the use of the respective amine in place ofn-butanol.

For Example 24 of Table 3, p-cyanocinnamaldehyde is used in Example 16in place of cinnamaldehyde, followed by esterification by the method ofExample 21.

EXAMPLE 25-30 Type Formula IV Ii) I l R -d c-n o 0| N N lo! TABLE 4Example Melting White- No. R Point C. ness 25 --OH 390 74.2 26 -OCH,359-360 l0l.l 27 -OC.H 228-9 98.2 28 --N C u 375 94 .2 29--NH(CH;):N(CH3), 284-! 63.0 30 -NHC,H, 367-8 96.5

These are synthesized by condensation of 4-amino-3- hydroxy-Z-naphthoicacid with glyoxal to give the bisdihydronaphthoxazole. This is oxidizedwith sodium hypochlorite to the sodium salt of the bis-naphthoxazole,which is converted to the'free acid or to the acid chloride, followed byreaction with an alcohol or a primary or secondary amine.

EXAMPLE 25 Preparation of 2,2-bis(9-carboxynaphth[l,2-d]oxazole A.Preparation of 2,2'-bis(2,3-dihydro-9-carboxynaphth[ l,2-d]-oxazole Amixture of 20.3 g. 4-amino-3-hydroxy-2-naphthoic acid, 250 ml. glacialacetic acid, and 7.36 g. 40 percent glyoxal is heated at 3435C. for 8hours. The product is filtered, washed with methanol, pressed betweenfilter paper and dried in vacuo over potassium hydroxide pellets. Yieldis 15.99 g., m.p. 244C. (dec.). Intense NH- absorption is shown at3,250cm' in the infra red spectrum.

B. Preparation of disodium 2,2'-bis(naphth[l,2- d]oxazole-9-carboxylate)A solution of 8.56 g. of Product A is mixed with 400 ml. diglyme, 200ml. water and 14 ml. N sodium hydroxide solution. It is cooled to 15C.and 48 g. of 12 percent sodium hypochlorite solution is added over 15minutes. Stirring is continued for 15 minutes and the excesshypochlorite destroyed with saturated sodium hydrosulfite solution to anegative test on starch iodide paper. This disodium salt product isfiltered, partially dried by stirring with 50 ml. methanol and dried byheating in a vacuum oven at 100l05C. Yield is 5.79 g. having a 375 71.0.

C. Preparation of 2,2'-bis(9-carboxynaphth[1,2-d] oxazole A l g. sampleof the product from part B above is dissolved in 700 ml. of hot waterand the solution is filtered. With stirring 2 ml. of 5N hydrochloricacid is added to the filtrate and after digesting l hour on the steambath the product is filtered. It is drained and washed with smallportions of water and drained on the funnel over night. Then it isslurried in acetone to get it into the form of a yellow powder, and itis dried at 60C. to give 0.82 g., m.p. 390C. The IR spectrum confirmsthe product. Maximum emission peaks occur at wavelengths of 433 nm and455 nm.

EXAMPLE 26 Preparation of dimethyl 2,2-bis(naphth[ l,2-d]oxazole-9-carboxylate) A mixture of 2.15 g. of the product ofExample 258 with 40 ml. of benzene and 50 ml. of thionyl chloride isrefluxed for 4 hours. The solvents are removed by concentration undervacuo and the acid chloride remaining as the residue is taken up in 50ml. of pyridine and 6 ml. of methanol. This mixture is refluxed for 3hours, cooled and filtered. The yellow precipitate is washed withmethanol, water and finally methanol again. It is dried at 60C. and thenrecrystallized from trichlorobenzene to obtain 1.54 g. of the product,m.p. 359-360C. The IR spectrum shows sharp absorption at 1,710 cm. andthe UV spectrum shows a 379 nm 90.3. Maximum UV emission peaks occur atwavelengths of433 nm and 456 nm.

EXAMPLE 27 Preparation of dibutyl 2,2-bis( naphth[ l,2-d]oxazole-9-carboxylate) A mixture of 2.34 g. disodium 2,2'-bis(naphth[l,2-d]-oxazole-9-carboxylate prepared in Example 258, 50 ml. benzene and 50ml. thionyl chloride is heated at reflux for 4 hours. The solvent isremoved under vacuo and residual thionyl chloride flushed out withbenzene twice under vacuo. The acid chloride product, identified by IRabsorption at 1,730 cm is taken up in a solution of 6 ml. butanol in5ml. pyridine. The mixture is heated at reflux for 3 hours. On cooling,the dibutyl ester product precipitates. It is filtered, washed withmethanol, with water and again with methanol. Dried at 60C. it gives2.37 g., m.p. 222232C. Recrystallized from monochlorobenzene and thenfrom n-butanol containing 10% monochlorobenzene, there is obtained 1.59g., m.p. 228229C. IR spectrum shows absorptivity at 1,710 cmf. UVspectrum shows a 317 um EXAMPLES 28-30 Preparation of2,2-bis((naphth[l,2-d]oxazole-9-carboxanilide) A mixture of the acidchloride prepared by the method of Example 27 from 2.52 g. of thedisodium salt prepared by the procedure of Example 258 is taken up in asolution of 2 ml. aniline in 50 ml. pyridine. The mixture is heated atreflux for 1% hours. The whole is cooled, the product filtered, washedwith water, methanol, and dried at 60C. There is obtained 2.73 g. of thehis anilide product, m.p. 378C. Its IR spectrum shows absorptivity at1,670 emf. Recrystallized twice from trichlorobenzene and dried at 180C.in vacuo, there is obtained 1.87 g. product having a UV spectrum a 383=59.4.

Other bis-amides are prepared by the same procedure and are shown asExamples 29 and 30 in Table 4.

EXAMPLE 31 weight of the individual brightener compound under test.

5. Unbrightened polyester fabric 6. Aluminum foil The sandwich is placedin a heated chamber (scorch tester) at 430F. for 1 minute. Thesublimation layer, number two, which receives brightener from the chipthrough the fiber glass fabric by sublimation, and the mark-off layer,number five, which receives brightener from contact with the chip arethen inspected under ultraviolet light and a visual observation is madeas to transfer of brightener from the chip at the high temperature.

The results of tests conducted on brightener compounds of this inventionand some prior art brighteners are given in Table 5 and show therelatively low sublimation tendency of the brightener compounds of thepresent invention.

Brlghtcncr Compound Ex. 2, Table l Ex. 9. Table 2 Ex. 12, Table 2 Ex.16, Table 3 Ex. l7, Table 3 Ex. 21, Table 3 Ex. l8, Table 3 Ex. 26,Table 4 Prior Art Compounds 2-styrylnaphth[ l ,2-d1- oxazole 2-(p-carbomethoxystyryb- 5 ,o-dimethylbenzoxazole 2-(3-chlor0styryl)-naphthl',2-d]oxazole 2-( 6-m ethylbenzoxazole-Z- yl-vinyl)benzoxazoleZ-stilbylnaphthl l ,2-d1- oxazole What I claim is:

TABLE 5 Sublimation none none none none none

none

very slight none heavy heavy very heavy heavy heavy moderate Mark-Offnone none trace none slight slight moderate heavy very heavy heavy veryheavy heavy heavy I. A 9-carboxylic naphthoxazole of the formula whereinY is a member of the group consisting of and in which R isbenztriazol-Z-yl or naphthtriazol-Z-yl, R is hydrogen, cyano or CO.R,and R is a member of the group consisting of the hydroxyl radical and amonovalent dchydro radical of an alcohol, a phenol, a

primary amine and a secondary amine, said monovalent radical containingone to about eight carbon atoms.

2. A Q-carboxylic naphthoxazole according to claim 1 having the formulain which R is benztriazol-Z-yl, or naphthtriazol-Z-yl and R is asdefined in claim 1.

3. A 9-carboxylic naphthoxazole according to claim 1 having the formulago G C' 0% in which R is as defined in claim 1.

4. A Q-carboxylic naphthoxazole according to claim 1 having the formulaIl -E E-R! l o\C C/o N/ \N I O

1. A 9-carboxylic naphthoxazole of the formula
 2. A 9-carboxylicnaphthoxazole according to claim 1 having the formula
 3. A 9-carboxylicnaphthoxazole according to claim 1 having the formula
 4. A 9-carboxylicnaphthoxazole according to claim 1 having the formula
 5. Dibutyl1,4-phenylene-bis(naphth(1,2-d)oxazole-2-yl-9-carboxylate. 6.2-(Naphtho(1,2-d)triazol2-yl-9-carbutoxy naphth (1,2-d)oxazole.